The present invention relates to aqueous dispersions of polymeric products. More particularly, this invention relates to ungelled polymeric products which are dispersed in aqueous medium and are stable in this condition but undergo a crosslinking reaction upon removal of the water.
In the field of acrylic polymers, it is known to polymerize alpha, beta-ethylenically unsaturated acids such as acrylic acid or methacrylic acid with other copolymerizable acrylic monomers such as styrene and methyl methacrylate to form polymers with unreacted carboxylic acid groups. These polymers can be treated with bases such as amines to form the polymeric salt which can be dispersed in water.
In preparing ungelled polymers, epoxy group-containing acrylic monomers such as glycidyl acrylate and glycidyl methacrylate are not employed because the epoxy group is reactive with the carboxyl group, particularly in the presence of amine, and gelling or crosslinking of the reactants will occur. This is shown in British Pat. No. 1,538,151 where crosslinked or gelled acrylic polymer articles are formed when alpha, beta-ethylenically unsaturated monocarboxylic acids such as methacrylic acid and epoxy group-containing compounds such as glycidyl methacrylate are copolymerized in a hydrocarbon diluent.
In the present invention, however, alpha, beta-ethylenically unsaturated acids such as acrylic acid and methacrylic acid and epoxy group-containing compounds which contain alpha, beta-ethylenic unsaturation such as glycidyl acrylate and methacrylate are polymerized in a fashion that gelation is avoided.